MANOMETRY
AND ELECTROPHYSIOLOGIC STUDIES
Manometry
and electrophysiologic studies are methods for eval-uating patients with GI
motility disorders. The manometry test measures changes in intraluminal
pressures and the coordinationof muscle activity in the GI tract. The pressures
can be recorded manually, on a physiograph, or on a computer.
Esophageal
manometry is used to detect motility disorders of the esophagus and the lower
esophageal sphincter. Patients must refrain from eating or drinking for 8 to 12
hours before the test. Medications that could have a direct affect on motility
(eg, cal-cium channel blockers, anticholinergic agents, sedatives) are
with-held for 24 to 48 hours. A pressure-sensitive catheter is inserted through
the nose and is connected to a transducer and a video recorder. The patient
then swallows small amounts of water while the resultant pressure changes are
recorded.
Gastroduodenal,
small-intestine, and colonic manometry are used to evaluate delayed gastric
emptying and gastric and in-testinal motility disorders such as irritable bowel
syndrome or atonic colon. This is often an ambulatory outpatient procedure
lasting 24 to 72 hours. Anorectal manometry measures the rest-ing tone of the
internal anal sphincter and the contractibility of the external anal sphincter.
It is helpful in evaluating patients with chronic constipation or fecal
incontinence and is useful in biofeedback for the treatment of fecal
incontinence. It can be performed in conjunction with rectal sensory
functioning tests. Phospho-Soda or a saline cleansing enema is administered 1
hour before the test. Positioning for the test is either the prone or the
lateral position.
A
rectal sensory function test is used to evaluate rectal sensory function and
neuropathy. A catheter and balloon are passed into the rectum, and the balloon
is inflated until the patient feels distention. Then the tone and pressure of
the rectum and anal sphincter are measured. The results are especially helpful
in the evaluation of patients with chronic constipation, diarrhea, or incontinence.
Electrogastrography,
an electrophysiologic study, also may be performed to assess gastric motility
disturbances. Electrodes are placed over the abdomen, and gastric electrical
activity is re-corded for up to 24 hours. Patients may exhibit rapid, slow, or
irregular waveform activity. Electrogastrography can be useful in detecting
motor or nerve dysfunction in the stomach.
Defecography
measures anorectal function. Very thick barium paste is instilled into the
rectum, and then fluoroscopy is per-formed to assess the function of the rectum
and anal sphincter while the patient attempts to expel the barium. The test
requires no preparation. The use of scintigraphic techniques to measure rectal
emptying of radioisotope-labeled artificial stool can provide more quantitative
information.
Electromyographic
(EMG) studies can supplement anorectal manometry to measure the integrity and
function of the anal sphincters in an effort to treat functional bowel
incontinence and constipation.
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